US9638063B2 - Steam turbine facility and method of operating the same - Google Patents

Steam turbine facility and method of operating the same Download PDF

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US9638063B2
US9638063B2 US14/475,847 US201414475847A US9638063B2 US 9638063 B2 US9638063 B2 US 9638063B2 US 201414475847 A US201414475847 A US 201414475847A US 9638063 B2 US9638063 B2 US 9638063B2
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Prior art keywords
drain
piping
steam
steam turbine
valve
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US20150068207A1 (en
Inventor
Daisuke Asakura
Koji Kanbe
Tsutomu Shioyama
Tomoo Oofuji
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Toshiba Corp
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Toshiba Corp
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
    • F01D25/00—Component parts, details, or accessories, not provided for in, or of interest apart from, other groups
    • F01D25/32—Collecting of condensation water; Drainage ; Removing solid particles
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01K—STEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES
    • F01K13/00—General layout or general methods of operation of complete plants
    • F01K13/006—Auxiliaries or details not otherwise provided for
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01K—STEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES
    • F01K7/00—Steam engine plants characterised by the use of specific types of engine; Plants or engines characterised by their use of special steam systems, cycles or processes; Control means specially adapted for such systems, cycles or processes; Use of withdrawn or exhaust steam for feed-water heating
    • F01K7/34—Steam engine plants characterised by the use of specific types of engine; Plants or engines characterised by their use of special steam systems, cycles or processes; Control means specially adapted for such systems, cycles or processes; Use of withdrawn or exhaust steam for feed-water heating the engines being of extraction or non-condensing type; Use of steam for feed-water heating
    • F01K7/38—Steam engine plants characterised by the use of specific types of engine; Plants or engines characterised by their use of special steam systems, cycles or processes; Control means specially adapted for such systems, cycles or processes; Use of withdrawn or exhaust steam for feed-water heating the engines being of extraction or non-condensing type; Use of steam for feed-water heating the engines being of turbine type
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16T—STEAM TRAPS OR LIKE APPARATUS FOR DRAINING-OFF LIQUIDS FROM ENCLOSURES PREDOMINANTLY CONTAINING GASES OR VAPOURS
    • F16T1/00—Steam traps or like apparatus for draining-off liquids from enclosures predominantly containing gases or vapours, e.g. gas lines, steam lines, containers
    • F16T1/38—Component parts; Accessories
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
    • F01D25/00—Component parts, details, or accessories, not provided for in, or of interest apart from, other groups
    • F01D25/08—Cooling; Heating; Heat-insulation
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02C—GAS-TURBINE PLANTS; AIR INTAKES FOR JET-PROPULSION PLANTS; CONTROLLING FUEL SUPPLY IN AIR-BREATHING JET-PROPULSION PLANTS
    • F02C6/00—Plural gas-turbine plants; Combinations of gas-turbine plants with other apparatus; Adaptations of gas-turbine plants for special use
    • F02C6/18—Plural gas-turbine plants; Combinations of gas-turbine plants with other apparatus; Adaptations of gas-turbine plants for special use using the waste heat of gas-turbine plants outside the plants themselves, e.g. gas-turbine power heat plants

Definitions

  • Embodiments described herein relate generally to a steam turbine facility and a method of operating the same.
  • a piping system of a steam turbine facility includes a steam piping system that guides steam generated by a boiler to a steam turbine.
  • the steam piping system includes drain piping that discharges drains produced from cold piping and equipment when the steam turbine is warmed-up for operation.
  • main steam piping the steam piping connected to a first-stage, high-pressure turbine is referred to as main steam piping.
  • Drain piping for warming-up is connected to various devices, e.g., a steam regulating valve for regulating a steam flow rate, connected to the main steam piping on the downstream thereof, and also to an inner casing surrounding a steam turbine main unit rotated by a steam power disposed further downstream.
  • a shut-off valve for adjusting the steam flow rate or shutting off the steam is interposed in each drain piping.
  • the drain produced during the warming-up is guided and drained into, for example, a condenser whose internal pressure is lower than that in the main steam piping and that of equipment.
  • the shut-off valve is closed after the warming-up is completed.
  • each main steam piping is provided with a main steam regulating valve having drain piping.
  • steam pressure fluctuations occur in a pipeline downstream of the main steam regulating valve, for example, at a portion in the main steam piping downstream of the main steam regulating valve, or at a portion in the drain piping downstream of a valve seat of the main steam regulating valve.
  • the steam pressure fluctuations in the main steam piping downstream of the main steam regulating valve are greater in the upper half-side main steam piping and smaller in the lower half-side main steam piping.
  • Pressure fluctuations occur also inside the inner casing that surrounds the rotating steam turbine due to, for example, current transformation of steam that flows in and the rotating turbine. This results in pressure fluctuations in the drain piping connecting to the inner casing.
  • a phenomenon is observed in which, in the drain piping connected to the main steam piping or the turbine casing, the temperature of the portion of the drain piping upstream of a shut-off valve abnormally increases during the load increase from the starting-up to the rated operation, if the shut-off valve is closed.
  • Such an abnormal increase of temperature causes material strength of the drain piping to be reduced.
  • stress produced in the piping by the piping pressure exceeds a permissible level of the piping material under the corresponding temperature, a failure such as burst might occur.
  • FIG. 1 is a perspective view showing a configuration of piping around a high-pressure turbine in a steam turbine facility in one example.
  • FIG. 2 is a perspective view showing a main steam stop valve shown in FIG. 1 .
  • FIG. 3 is a piping diagram showing a section around the high-pressure turbine in the steam turbine facility.
  • FIG. 4 is a diagram schematically showing a configuration of piping included in an area 100 shown in FIG. 3 .
  • FIG. 5 is a diagram schematically showing a configuration of the high-pressure turbine and the piping included in an area 101 in FIG. 3 .
  • FIG. 6 is a diagram schematically showing a configuration of the piping included in the area 100 shown in FIG. 3 according to a first embodiment.
  • FIG. 7 shows cross-sectional views showing a configuration of a heat absorber disposed in an area 101 A shown in FIG. 6 , where (a) is a longitudinal cross-sectional view and (b) is a transverse cross-sectional view.
  • FIG. 8 shows cross-sectional views showing a heat absorber according to another embodiment, where (a) is a longitudinal cross-sectional view and (b) is a transverse cross-sectional view.
  • FIG. 9 shows cross-sectional views showing a heat absorber according to still another embodiment, where (a) is a longitudinal cross-sectional view and (b) is a transverse cross-sectional view.
  • FIG. 10 shows cross-sectional views showing a heat absorber according to a further embodiment, where (a) is a longitudinal cross-sectional view and (b) is a transverse cross-sectional view.
  • FIG. 11 is a diagram schematically showing a configuration of the piping included in the area 100 shown in FIG. 3 according to a second embodiment.
  • FIG. 12 shows perspective views showing a structure of a heat-insulating jacket removably disposed in the drain piping shown in FIG. 11 , where (a) shows a condition in which the heat-insulating jacket is opened and (b) shows a condition in which the heat-insulating jacket is closed (in a mounted condition).
  • FIG. 13 is a diagram schematically showing a configuration of the piping included in the area 100 shown in FIG. 3 according to a third embodiment.
  • FIG. 14 shows perspective views showing a mesh jacket removably disposed in the drain piping shown in FIG. 13 , where (a) shows a condition in which the mesh jacket is opened and (b) shows a condition in which the mesh jacket is closed (in a mounted condition).
  • FIG. 15 is a view schematically showing a configuration of drain piping according to a fourth embodiment.
  • FIG. 16 shows perspective views showing variations of fins disposed on the outer surface of the drain piping according to the fourth embodiment
  • FIG. 17 is a piping diagram for illustrating refrigerant supply in a configuration in which a cooling structure according to the fourth embodiment is disposed in the drain piping downstream of a main steam regulating valve;
  • FIG. 18 is a piping diagram for illustrating refrigerant supply in a configuration in which the cooling structure according to the fourth embodiment is disposed in the drain piping of an inner casing for the high-pressure turbine;
  • FIG. 19 is a diagram schematically showing a cross section of a pipe and a jet-generating nozzle for illustrating a pipe wall temperature increasing when a pipe end is closed;
  • FIG. 20 is a diagram schematically showing the cross section of the pipe and the jet-generating nozzle for illustrating the pipe wall temperature not increasing when the pipe end is open;
  • FIG. 21 is a diagram schematically showing a test setup.
  • FIG. 22 is a graph showing measurements of the pipe wall temperature when the pipe end is closed or open.
  • the embodiments described herein generally relate to a technique that prevents abnormal overheating of drain piping with a shut-off valve in a steam turbine facility.
  • the embodiments generally provide a steam turbine facility which includes: a steam turbine including a turbine casing; main steam piping that supplies steam from a boiler to the steam turbine; a main steam regulating valve provided in the main steam piping to adjust a flow rate of steam supplied to the steam turbine; drain piping in which a shut-off valve is provided, the drain piping being either a valve drain pipe that leads a drain from the main steam regulating valve to an outside thereof, or a casing drain pipe that leads a drain from the turbine casing to an outside thereof.
  • a heat absorber is disposed in a range, upstream of the shut-off valve, of the drain piping to absorb heat of the drain piping.
  • a cover is provided to surround a range, upstream of the shut-off valve, of the drain piping to prevent contact with a surface of the drain piping, the cover being configured to allow a gas to flow therethrough, wherein no heat-insulating material is disposed around the drain piping in the range.
  • a removable heat-insulating jacket is disposed to surround a range, upstream of the shut-off valve, of the drain piping. In this case, an operation is possible in which, when an abnormal overheat can occur in the drain piping, the heat-insulating jacket may be removed.
  • a refrigerant path disposed to surround the drain piping, the refrigerant path cooling the drain piping; and a refrigerant circulating arrangement that circulates refrigerant through the refrigerant path.
  • the refrigerant may be passed through the refrigerant path.
  • Each of the embodiments to be described hereunder relates to a configuration for preventing abnormal overheating occurring in drain piping due to a thermoacoustic effect, which is described in detail later.
  • an example of drain piping for which an abnormal overheating preventive measure is taken and a portion of a steam turbine facility around the drain piping are described with reference to FIGS. 1 to 5 .
  • a high-pressure turbine 200 has an upper half and a lower half, to which upper half-side main steam piping 11 and lower half-side main steam piping 12 are respectively connected so as to supply steam thereto from a boiler (not shown).
  • FIG. 1 shows an exemplary configuration having two sets of the upper half-side main steam piping 11 and two sets of the lower half-side main steam piping 12 .
  • the upper half-side main steam piping 11 is provided therein with an upper half-side main steam stop valve 20 to shut off steam supplied from the boiler (not shown) to the high-pressure turbine 200 .
  • the upper half-side main steam piping 11 is further provided therein with an upper half-side main steam regulating valve 30 downstream of the upper half-side main steam stop valve 20 to adjust a flow rate of the steam to be supplied to the high-pressure turbine 200 .
  • the lower half-side main steam piping 12 is provided therein with a lower half-side main steam stop valve 40 to shut off the steam supplied from the boiler (not shown) to the high-pressure turbine 200 .
  • the lower half-side main steam piping 12 is further provided with a lower half-side main steam regulating valve 50 downstream of the lower half-side main steam stop valve 40 to adjust the flow rate of the steam to be supplied to the high-pressure turbine 200 .
  • FIG. 1 shows an exemplary configuration in which the upper half side of the high-pressure turbine 200 and the upper half-side main steam piping 11 (including the upper half-side main steam stop valve 20 and the upper half-side main steam regulating valve 30 ) are disposed above a floor portion 210 that may be called an operating floor, and in which the lower half side of the high-pressure turbine 200 and the lower half-side main steam piping 12 (including the lower half-side main steam stop valve 40 and the lower half-side main steam regulating valve 50 ) are disposed below the floor portion 210 .
  • the portion of the upper half-side main steam piping 11 downstream of the upper half-side main steam regulating valve 30 (the portion is commonly called “main steam lead pipe”) has a complicated piping layout including, for example, a straight pipe 11 b disposed between an elbow pipe 11 a and an elbow pipe 11 a.
  • the lower half-side main steam piping 12 downstream of the lower half-side main steam regulating valve 50 very often has a relatively simple piping layout mainly including horizontal pipes, as compared with the upper half-side main steam piping 11 .
  • the upper half-side main steam stop valve 20 and the lower half-side main steam stop valve 40 are configured similarly to each other.
  • the upper half-side main steam regulating valve 30 and the lower half-side main steam regulating valve 50 are also configured similarly to each other.
  • drain piping disposed in the upper half-side main steam stop valve 20 and the upper half-side main steam regulating valve 30 shown in FIG. 2 will only be described to represent configurations in the lower half-side main steam stop valve 40 and the lower half-side main steam regulating valve 50 .
  • the upper half-side main steam stop valve 20 has an ante-valve-seat drain pipe 21 for draining a drain upstream of a valve seat and a post-valve-seat drain pipe 22 for draining a drain downstream of the valve seat.
  • the upper half-side main steam regulating valve 30 has a post-valve-seat drain pipe 31 for draining a drain downstream of a valve seat.
  • an ante-valve-seat drain pipe for the lower half-side main steam stop valve 40 is denoted by reference numeral 41 and a post-valve-seat drain pipe for the lower half-side main steam stop valve 40 is denoted by reference numeral 42 .
  • a post-valve-seat drain pipe for the lower half-side main steam regulating valve 50 is denoted by reference numeral 51 .
  • Each of the drain pipes ( 21 , 22 , 31 , 41 , 42 , 51 ) has a terminal end communicating with, for example, a condenser (not shown) whose internal pressure is lower than that of the drain pipe.
  • a condenser not shown
  • opening the shut-off valve disposed in each drain pipe causes the drain to be fed to the condenser because of the differential pressure.
  • a shut-off valve (see, for example, shut-off valves 60 , 60 ′ shown in FIG. 3 ) is disposed in each of the drain pipes ( 21 , 22 , 31 , 41 , 42 , 51 ).
  • the shut-off valve in each drain pipe is opened during warming-up of the high-pressure turbine 200 so that the drain produced in the upper half-side main steam piping 11 or the lower half-side main steam piping 12 is fed to the condenser.
  • the shut-off valve in each drain pipe is closed after the warming-up is completed in order to minimize loss of steam energy for rotating the high-pressure turbine 200 .
  • the post-valve-seat drain pipe 31 is connected to the upper half-side main steam regulating valve 30 so as to branch from the upper half-side main steam piping 11 .
  • the shut-off valve 60 is disposed in a downstream area of the post-valve-seat drain pipe 31 .
  • the post-valve-seat drain pipe 31 leads to the condenser (not shown) provided on the right of what are shown in FIG. 3 . Specifically, the drain produced during warming-up is drained to the condenser.
  • FIG. 4 is a diagram schematically showing an area 100 enclosed by a dash-single-dot line in FIG. 3 .
  • a stream of the steam flowing through the inside of the upper half-side main steam piping 11 is indicated by an arrow 1000 .
  • the upper half-side main steam piping 11 downstream of the upper half-side main steam regulating valve 30 leads to an inlet of the high-pressure turbine 200 .
  • the inner casing drain pipe 33 for draining a drain produced during warming-up of the high-pressure turbine 200 is connected to an inner casing inlet of the high-pressure turbine 200 .
  • the shut-off valve 60 ′ is disposed downstream of the inner casing drain pipe 33 .
  • FIG. 5 is a diagram schematically showing an area 101 enclosed by a dash-double-dot line in FIG. 3 .
  • the area 101 includes an internal configuration of the high-pressure turbine 200 .
  • the stream of the steam is indicated by the arrow 1000 .
  • the main steam flows through the inside of the upper half-side main steam piping 11 downstream of the upper half-side main steam regulating valve 30 , and reaches the high-pressure turbine 200 .
  • the high-pressure turbine 200 has a dual casing structure comprising an inner casing 204 and an outer casing 205 .
  • Turbine rotor blades 202 rotated by steam energy are disposed inside the inner casing 204 .
  • a small chamber called a nozzle box 201 is disposed at a steam inlet portion of the inner casing 204 .
  • the steam that has reached the high-pressure turbine 200 is guided into this nozzle box 201 .
  • the steam that has reached the nozzle box 201 flows rightwardly from the left in FIG. 5 while rotating the turbine rotor blades 202 , flows out to a main steam exhaust pipe 203 , and returns to the boiler (not shown).
  • the steam returned to the boiler is reheated by the boiler and supplied to a medium-pressure turbine (not shown).
  • the inner casing drain pipe 33 for collecting the drain produced during warming-up of the equipment including the high-pressure turbine 200 and the steam piping, is connected to the nozzle box 201 .
  • the shut-off valve 60 ′ is provided in the inner casing drain pipe 33 .
  • the drains produced in the upper half-side main steam piping 11 and in various equipment are passed through the inner casing drain pipe 33 , and are drained to and collected in the condenser (not shown), which is connected to the inner casing drain pipe 33 at a point downstream of the shut-off valve 60 ′.
  • the foregoing steam turbine facility is mere an example, and thus various configurations are possible.
  • the exhaust steam having finished the work in the high-pressure turbine 200 is not reheated by the boiler; instead, the exhaust steam is guided into steam piping called “cross-around piping” to be directly fed to a subsequent low-pressure turbine to rotate it.
  • a common measure for preventing the abnormal overheating can be applied to both the post-valve-seat drain pipe 31 and the inner casing drain pipe 33 .
  • a case in which the abnormal overheating measure is applied to the post-valve-seat drain pipe 31 will representatively be described below.
  • the “post-valve-seat drain pipe 31 ” is also referred to as a “drain pipe 31 ”
  • the “upper half-side main steam piping 11 ” is also referred to as “steam piping 11 ”
  • the “upper half-side main steam regulating valve 30 ” is also referred to as a “steam regulating valve 30 ”, hereinafter.
  • FIG. 6 shows a piping configuration in the first embodiment.
  • the steam piping 11 the steam regulating valve 30 , the drain pipe 31 , and the shut-off valve 60 are covered in a heat-insulating material 13 that may, for example, be called as a “heat insulator” by one of ordinary skill in the art. It is common practice in steam turbine facilities to apply the heat-insulating material 13 to the portions cited above.
  • the heat-insulating material 13 for the steam piping 11 and the steam regulating valve 30 is applied mainly to prevent heat dissipation from the surfaces of the steam piping 11 and the steam regulating valve 30 to the atmosphere, thereby preventing plant efficiency from being reduced due to a reduced main steam temperature. Meanwhile, the heat-insulating material 13 on the drain pipe 31 is mainly intended to protect an operator or a worker from burns, in addition to preventing the plant efficiency from being reduced.
  • the range is indicated as an area 100 A enclosed by a broken line in FIG. 6 .
  • a heat absorber 90 formed of a metal is attached so as to surround the drain pipe 31 beneath the heat-insulating material 13 as shown in FIG. 7 over the entire area 100 A or a part of the area 100 A shown in FIG. 6 .
  • the heat absorber 90 is a generally rectangular, ring-shaped plate having a hole at a center thereof, the hole having an inside diameter corresponding to an outside diameter of the drain pipe 31 .
  • the heat absorber 90 comprises two heat absorber half bodies 90 a , 90 b .
  • the half bodies 90 a , 90 b are fixed to the drain pipe 31 as follows: specifically, the half bodies 90 a , 90 b are placed on the drain pipe 31 so as to sandwich the drain pipe 31 and two bolts 73 are then fastened together.
  • the heat absorber 90 achieves the following effect. Specifically, even when the abnormal overheating occurs in the drain pipe 31 , the heat in the drain pipe 31 is transmitted to the heat absorber 90 through heat conduction. This reduces a rise in temperature of the drain pipe 31 , thereby preventing the drain pipe 31 from, for example, being broken.
  • Examples of the material used for the heat absorber 90 include the metal used for the drain pipe 31 , e.g. iron, and metallic materials having a high thermal conductivity, e.g. copper and aluminum.
  • an outer peripheral surface of the drain pipe 31 and an inner peripheral surface of the hole in the heat absorber 90 are in close contact with each other while leaving no gap or smallest possible gaps therebetween, which increases an amount of heat transferred from the drain pipe 31 to the heat absorber 90 .
  • a thin metal plate, metal tape, metal plating, or the like filling the gaps between the drain pipe 31 and the heat absorber 90 may be applied to at least either one of the drain pipe 31 and the heat absorber 90 .
  • the mass required for the heat absorber 90 by itself to absorb heat of the drain pipe 31 is estimated.
  • the total mass of a plurality of heat absorbers 90 is considered to be heat capacity equivalent mass.
  • the drain pipe 31 in the actual facility has an outside diameter of 48.3 mm and a thickness of 10 mm
  • the drain pipe 31 weighs about 9.6 kg per meter. A mass of about 9.6 kg or more is thus required for the heat absorber 90 .
  • a space (cavity) 14 is left between adjacent heat absorbers 90 , instead of the heat-insulating material 13 being disposed therebetween. Specifically, it is preferable that there is a space 14 is enclosed by an inner surface of the heat-insulating material 13 , side surfaces of the heat absorber 90 , and the outer peripheral surface of the drain pipe 31 .
  • FIG. 8 shows a heat absorber in another embodiment.
  • This heat absorber 91 shown in FIG. 8 is a generally circular, ring-shaped plate having a hole at a center thereof, the hole having an inside diameter corresponding to an outside diameter of the drain pipe 31 .
  • the heat absorber 91 comprises two heat absorber half bodies 91 a , 91 b .
  • the half bodies 91 a , 91 b are fixed to the drain pipe 31 as follows: specifically, the half bodies 91 a , 91 b are placed on the drain pipe 31 so as to sandwich the drain pipe 31 and integrated with each other through a fillet weld 72 via a welding piece 71 .
  • FIG. 8 omits showing the heat-insulating material. If the heat-insulating material is to be disposed, preferably, a space (cavity) is left between adjacent heat absorbers 91 , instead of the heat-insulating material being disposed therebetween, just as in the case shown in FIG. 7 .
  • FIG. 9 shows cross-sectional views showing a heat absorber according to still another embodiment.
  • the heat absorber 92 shown in FIG. 9 has a length such that a relatively long range of the drain pipe 31 , or an entire or substantially entire range of the area 100 A of the drain pipe 31 can be covered by a single heat absorber 92 .
  • the heat absorber 92 shown in FIG. 9 comprises two half bodies 92 a , 92 b that are fastened together with bolts 73 to be fixed to the drain pipe 31 .
  • the heat absorber 92 shown in FIG. 9 may be fixed to the drain pipe 31 by welding similar to that used with the heat absorber 91 shown in FIG. 8 .
  • the heat absorber 92 shown in FIG. 9 has an outside diameter equal to that of the heat absorber 91 shown in FIG. 8 , the heat absorber 92 shown in FIG. 9 has greater total mass for the zero clearance between the adjacent heat absorbers, so that capacity of heat to be absorbed from the drain pipe 31 can be increased. On the other hand, weight per heat absorber increases, which degrades ease of installation.
  • FIG. 10 shows a heat absorber in yet another embodiment.
  • FIG. 10 shows a configuration in which part of the drain pipe 31 having an ordinary wall thickness is replaced by a thick-walled pipe 93 .
  • the drain pipe 31 comprises a first portion 31 a that is a drain pipe portion having an ordinary wall thickness and a thick-walled second portion 31 b joined to the first portion 31 a through welding or other joining technique.
  • a portion of the thick-walled pipe 93 specifically, the second portion 31 b disposed radially outside of an outer peripheral surface of the first portion 31 a provides the heat absorber.
  • the configuration shown in FIG. 10 may be achieved by cutting out part of the existing drain pipe 31 and then joining the thick-walled pipe 93 to the cutout portion.
  • the configuration may be achieved by installing a drain pipe 31 having varying wall thicknesses at the initial installation of the plant.
  • the heat absorbers 90 to 93 absorb heat, thereby preventing the drain pipe 31 from abnormally overheating.
  • the drain pipe 31 can thus be prevented from bursting.
  • the heat-insulating material 13 around the drain pipe 31 may be omitted.
  • the drain pipe 31 can be prevented from overheating through a relatively simple procedure of peeling off the heat-insulating material 13 from the existing drain pipe 31 and additionally installing the heat absorbers 90 to 93 .
  • a step of installing the heat-insulating material 13 simply needs to be added to the above-described procedure.
  • a measure can be taken in an existing plant through a relatively simple procedure to prevent piping from overheating as caused by the thermoacoustic effect.
  • a second embodiment will be described below with reference to FIGS. 11 to 14 .
  • the second embodiment eliminates the heat-insulating material 13 or allows the heat-insulating material 13 to be removed as necessary in order to improve heat dissipation from the drain pipe 31 for the prevention of overheating of the drain pipe 31 .
  • the same parts are designated by the same reference numerals as those used in the first embodiment and descriptions for those parts will be omitted or simplified.
  • the heat-insulating material 13 is disposed, as has conventionally been done, on the steam piping 11 , the steam regulating valve 30 , and the drain pipe 31 downstream of the shut-off valve 60 .
  • the heat-insulating material 13 is not, however, disposed on at least part of a range in the drain pipe 31 from the branch point from the steam piping 11 to the shut-off valve 60 (the area 100 A shown in FIG. 6 ), preferably an entire or substantially entire area of the range.
  • the reasons that the steam turbine facility is provided with the heat-insulating material are to prevent thermal loss arising from the steam turbine efficiency, and to prevent burns.
  • the shut-off valve 60 is closed at almost all time during the operation of the steam turbine, there is no steam flow in the drain pipe 31 .
  • the drain pipe 31 there is no problem of thermal loss causing the reduction of the turbine rotation efficiency.
  • the only possible risk involved in the operation of the facility associated with the removal of the heat-insulating material 13 from the drain pipe 31 as shown in FIG. 11 is that a plant worker, for example, inadvertently touches the drain pipe 31 and gets burned.
  • the heat-insulating material 13 can therefore be removed from the drain pipe 31 by calling the plant worker's attention, providing an alternative device for preventing a possible contact by the worker, and taking related measures.
  • the abnormal overheating of the drain pipe 31 occurs for only a limited short period of time.
  • a mode of operation is thus possible in which the heat-insulating material 13 is removed from the drain pipe 31 only during a time period in which the abnormal overheating occurs and is mounted on the drain pipe 31 in other time periods.
  • FIG. 12 shows a heat-insulating jacket 19 suitable in such an application as that described above.
  • the heat-insulating jacket 19 comprises a heat-insulating material or a combination of a heat-insulating material covered in a jacket, having a generally cylindrical shape.
  • the heat-insulating jacket 19 has a hole with an inside diameter corresponding to the outside diameter of the drain pipe 31 .
  • the heat-insulating jacket 19 includes two half bodies 19 a , 19 b connected to each other by hinges (hinge joints) 17 .
  • Each of the half bodies 19 a , 19 b has a groove 19 c having a semicircular cross section.
  • the heat-insulating jacket 19 has spring fasteners (locking devices) 70 for maintaining a closed position of the two half bodies 19 a , 19 b (see FIG. 12( b ) ).
  • the heat-insulating jacket 19 can be manually mounted on, or removed from, the drain pipe 31 easily.
  • the drain pipe 31 is fitted in the groove 19 c in the half body 19 a
  • the other half body 19 b is placed over the drain pipe 31 and the half body 19 a
  • the half bodies 19 a , 19 b are then locked in place with the spring fasteners 70 .
  • An appropriate type of working robot may even be applied to mount or remove the heat-insulating jacket 19 .
  • the method for fixing the heat-insulating jacket 19 to the drain pipe 31 shown in FIG. 12 is not the only possible method.
  • the two half bodies 19 a , 19 b of the heat-insulating jacket 19 may be maintained in the closed position using screw bolts.
  • FIGS. 13 and 14 show configurations that ensure proper heat dissipation from the drain pipe 31 and prevent burns.
  • the configurations each include a mesh jacket 15 , instead of the conventional heat-insulating material, disposed so as to surround the drain pipe 31 .
  • the heat-insulating material 13 is removed from the drain pipe 31 over a range from its branch point from the steam piping 11 to the shut-off valve 60 , specifically, the range over which the abnormal overheating can occur and, instead, a mesh jacket 15 is installed over the range.
  • the mesh jacket 15 offers good ventilation.
  • installing a blower 80 as shown in FIG. 13 allows the drain pipe 31 to be forcedly air-cooled via the mesh jacket 15 .
  • the blower 80 may be omitted.
  • the steam turbine facility is operated such that the blower 80 is operated only under a condition in which the abnormal overheating due to the foregoing thermoacoustic effect may occur and the blower 80 is stopped under any other conditions.
  • the mesh jacket 15 is safe from the standpoint of strength. If a material having a high thermal conductivity is used, however, the mesh jacket 15 may have a surface temperature that can cause burns because of heat transfer and radiant heat from the drain pipe 31 involved. To achieve safer prevention of burns, therefore, it is appropriate to manufacture the mesh jacket 15 from a material having as low a thermal conductivity as possible, e.g., an inorganic, hard heat-resisting material.
  • the mesh jacket 15 includes two half bodies 15 a , 15 b connected to each other by a hinge (hinge joint) 17 .
  • the half bodies 15 a , 15 b each have a fastening plate 16 having a plurality of, three in the example shown in FIG. 14( a ) , holes 16 a .
  • the half bodies 15 a , 15 b each have semicircular cutouts 15 c formed in both sides thereof.
  • the cutouts 15 c receive the drain pipe 31 passed therethrough.
  • the cutouts 15 c have an inside diameter not smaller than the outside diameter of the drain pipe 31 .
  • the mesh jacket 15 can be mounted over the drain pipe 31 as follows. Specifically, referring to FIG. 14( b ) , the two half bodies 15 a , 15 b are mated with each other and closed so as to sandwich the drain pipe 31 and the half bodies 15 a , 15 b are fastened together using bolts and nuts 74 installed in the holes 16 a in the fastening plates 16 .
  • the mesh jacket 15 though shown in FIG. 14 as a rectangular parallelepiped, may have any other shape, e.g., a cylinder.
  • the second embodiment described above promotes heat dissipation from the drain pipe 31 , thereby preventing the temperature on the inner surface of the drain pipe 31 from increasing abnormally due to the thermoacoustic effect.
  • the third embodiment includes a refrigerant path disposed around the drain pipe 31 , the refrigerant path allowing a refrigerant to flow therethrough to thereby cool the drain pipe 31 .
  • the specific portion cooled in the drain pipe 31 is the same as that in the first and second embodiments.
  • a dual pipe structure is formed by disposing a sheath pipe 46 on the outside of the drain pipe 31 , the sheath pipe 46 having an inside diameter larger than the outside diameter of the drain pipe 31 .
  • a space between the drain pipe 31 and the sheath pipe 46 is used as a refrigerant path 46 a .
  • a flow of a fluid including a drain comprising steam and a condensate flowing through the drain pipe 31 is indicated by an arrow 300 and a flow of the refrigerant flowing through the refrigerant path 46 a is indicated by an arrow 301 .
  • the flow of the fluid in the drain pipe 31 and the flow of the refrigerant in the refrigerant path 46 a need not be in opposite directions, but may be in the same direction.
  • the shut-off valve 60 is disposed downstream in the drain pipe 31 on the right of what is shown in FIG. 15 .
  • the shut-off valve 60 is closed, the working fluid 300 does not flow and remains stagnant.
  • the drain pipe 31 shown in FIG. 15 has an ordinary cylindrical outer surface. This is, however, not the only possible configuration and, alternatively, fins 47 , 48 , 49 may be attached to the outer surface of the drain pipe 31 as shown in FIG. 16 . This increases an area of the drain pipe 31 in contact with the refrigerant, thereby promoting heat exchange between the fluid in the drain pipe 31 and the refrigerant in the refrigerant path 46 a and improving cooling efficiency.
  • FIG. 16 illustrates possible fin configurations, and the fin configurations are not limited thereto.
  • a refrigerant supply device for the refrigerant path 46 a will be described below with reference to FIGS. 17 and 18 .
  • FIGS. 17 and 18 descriptions for like elements shown in FIG. 3 will be omitted.
  • the sheath pipe 46 described with reference to FIG. 15 covers the section of the drain pipe 31 extending from the position near the branch point from the steam piping 11 to the position near the shut-off valve 60 , thus forming a dual pipe structure.
  • a refrigerant supply pipe 61 and a refrigerant discharge pipe 62 are connected to the refrigerant path 46 a formed by the dual pipe structure.
  • Valves 63 , 64 are disposed in the supply pipe 61 and the discharge pipe 62 , respectively. Either one of the valves 63 , 64 may be omitted.
  • the drain pipe 31 can be prevented from the abnormal overheating by opening the valves 63 , 64 to thereby cause the refrigerant to flow through the refrigerant path 46 a and the drain pipe 31 to cooled when the thermoacoustic effect can cause abnormal overheating of the drain pipe 31 .
  • the direction in which the refrigerant flows at this time is indicated by the arrow in FIG. 17 .
  • the abnormal overheating very often stops when the steam turbine is in the steady-state loading condition.
  • the refrigerant may be stopped from flowing.
  • the refrigerant used whether it be liquid or gas, only needs to have a temperature lower than the conventional design temperature of the drain pipe.
  • bleed steam supplied from a bleed pipe 65 of the high-pressure turbine 200 is used as the refrigerant will be described below with reference to FIG. 18 .
  • the bleed steam is supplied to the refrigerant path 46 a via the supply pipe 61 and returned to the main steam exhaust pipe 203 of the high-pressure turbine 200 via the discharge pipe 62 .
  • Steam bleed extracted from a middle stage of the high-pressure turbine 200 flows through the sheath pipe 46 . Because part of this steam has done work of rotating the high-pressure turbine 200 , the steam has a temperature lower than the main steam temperature. Specifically, the steam, having a temperature sufficiently lower than the temperature of the drain pipe 31 , can be said to function as a refrigerant for preventing abnormal overheating of the drain pipe 31 .
  • a configuration is also possible to replace the example shown in FIG. 18 with, for example, a boiler water supply system.
  • the configuration draws water that serves as the refrigerant from a high-pressure water supply pipe and supplies the water to the refrigerant path 46 a , so that the water as the refrigerant can escape to a low-pressure water supply pipe by way of the discharge pipe 62 .
  • the water is the refrigerant.
  • cooling the drain pipe 31 allows the inner surface temperature of the drain pipe 31 to be prevented from overheating abnormally because of the thermoacoustic effect involved.
  • the refrigerant path 46 a can be achieved by not only the dual pipe structure, but also, for example, incorporating a refrigerant path in the drain pipe 31 or providing a refrigerant path through another structure.
  • the following describes how the abnormal overheating occurs in the drain pipe 31 .
  • P1 is a dimensionless pressure amplitude
  • K is a constant
  • ⁇ is a ratio of specific heat
  • ⁇ is a coefficient of viscosity
  • a is an acoustic velocity
  • ⁇ is a boundary layer thickness
  • R is an inside diameter of the cylinder.
  • An inner peripheral length of the cylinder is ⁇ R.
  • a heating value Q(W/m) of the cylinder per unit length can thus be obtained using expression (3).
  • ⁇ is a coefficient of kinematic viscosity
  • FIG. 19 schematically shows a cross section of a pipe 220 and a jet-generating nozzle 230 for illustrating a pipe wall temperature increasing with a closed end 222 of the pipe 220 .
  • FIG. 20 schematically shows the cross section of the pipe 220 and the jet-generating nozzle 230 for illustrating the pipe wall temperature not increasing with an open end 223 of the pipe 220 .
  • T be the pipe wall temperature of the pipe 220 .
  • Q(W/m) of the pipe 220 per unit length caused by the thermoacoustic effect can be obtained using expression (5).
  • c is a specific heat of the material of the pipe 220
  • ⁇ is density of the material of the pipe 220
  • ⁇ is thermal conductivity of the material of the pipe 220 .
  • A is a cross-sectional area of the pipe 220
  • h is natural convection thermal conductivity of the pipe 220 relative to surroundings
  • D is a perimeter of the pipe 220
  • T ⁇ is an ambient temperature.
  • v is an average flow velocity of a flow through the pipe 220
  • ⁇ is a temperature of the fluid in the pipe 220
  • cf is a specific heat of the fluid in the pipe 220
  • ⁇ f is density of the fluid in the pipe 220
  • Af is a flow path cross-sectional area of the pipe 220
  • x is an axial coordinate of the pipe 220 .
  • the pipe 220 is a steel pipe having a low thermal conductivity and protected by a heat insulator
  • the second and third terms of the right side in expression (6) are omitted and expression (6) can be approximated by expression (7).
  • the temperature of the fluid in the pipe 220 can be approximated to be substantially equal to the pipe wall temperature T of the pipe 220 . If the relation of expression (9) is satisfied in expression (8), the cooling effect by the flow through the pipe 220 is greater than the heating effect by the thermoacoustic effect, resulting in the pipe wall temperature T being reduced.
  • FIG. 21 schematically shows a test setup. It is noted that FIG. 21 represents a condition in which the pipe 220 has open ends.
  • a stainless-steel pipe 220 was used, the pipe 220 having a length of 360 mm, an inside diameter of 10 mm, and an outside diameter of 120 mm.
  • an angle ⁇ formed between a straight line L perpendicular to a central axis Ot of the pipe 220 and a central axis On of the nozzle 230 was 80 degrees.
  • Air with a temperature of 20° C. was jetted from the nozzle 230 in the atmosphere of 20° C.
  • a ratio of pressure Pn immediately upstream of a jet port of the nozzle 230 to atmospheric pressure Pa (Pa/Pn) was 0.44.
  • An outer wall temperature of the pipe 220 at an axial center position of the pipe 220 was measured with a thermocouple. The measured temperature was assumed to be the pipe wall temperature. When the pipe 220 had a closed second end, the second end was closed with a lid.
  • FIG. 22 shows measurements of the pipe wall temperature when the pipe end is closed or open. The measurements were taken when the pipe end was opened, closed, and then opened with a jet from the nozzle 230 colliding with one end of the pipe.
  • FIG. 22 reveals that the pipe wall temperature increases only while the pipe end is closed.
  • FIG. 22 further reveals that opening the pipe end from its closed position quickly cools the pipe wall.
  • the above-described embodiments can prevent the abnormal overheating in the steam turbine piping system and thus provide highly reliable steam turbine piping.
  • each of the above-described embodiments is applicable as the drain piping that reportedly develops the abnormal overheating due to the thermoacoustic effect to the post-valve-seat drain pipe 31 of the upper half-side main steam regulating valve 30 and the inner casing drain pipe 33 in the high-pressure turbine 200 .
  • the configuration of each of the above-described embodiments is nonetheless applicable to any piping with a shut-off valve in which the abnormal overheating due to the thermoacoustic effect is confirmed, e.g., drain piping.
  • the configuration of each of the above-described embodiments may be applied, for example, to a range that extends from a position at which the inner casing drain pipe 33 leaves the outer casing 205 to a position near the shut-off valve 60 ′.

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Control Of Turbines (AREA)
  • Lift Valve (AREA)
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CN106968735B (zh) * 2017-05-31 2019-05-03 西安石大能源股份有限公司 余热发电装置
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US4291538A (en) * 1980-01-04 1981-09-29 Chicago Bridge & Iron Company Power producing dry cooling apparatus and method
US4691522A (en) * 1983-04-18 1987-09-08 Brown Ii William G Solar power generation
US4811566A (en) * 1987-08-21 1989-03-14 Westinghouse Electric Corp. Method and apparatus for removing moisture from turbine exhaust lines
US20100050637A1 (en) * 2008-09-04 2010-03-04 Kabushiki Kaisha Toshiba Carbon-dioxide-capture-type steam power generation system
US8567196B2 (en) * 2009-08-28 2013-10-29 Kabushiki Kaisha Toshiba Steam turbine power plant and operating method thereof

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Publication number Priority date Publication date Assignee Title
US4052858A (en) * 1975-01-08 1977-10-11 Jeppson Morris R Method and apparatus integrating water treatment and electrical power production
US4291538A (en) * 1980-01-04 1981-09-29 Chicago Bridge & Iron Company Power producing dry cooling apparatus and method
US4691522A (en) * 1983-04-18 1987-09-08 Brown Ii William G Solar power generation
US4811566A (en) * 1987-08-21 1989-03-14 Westinghouse Electric Corp. Method and apparatus for removing moisture from turbine exhaust lines
US20100050637A1 (en) * 2008-09-04 2010-03-04 Kabushiki Kaisha Toshiba Carbon-dioxide-capture-type steam power generation system
US8567196B2 (en) * 2009-08-28 2013-10-29 Kabushiki Kaisha Toshiba Steam turbine power plant and operating method thereof

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